class Solution {
public:
    TreeNode* pruneTree(TreeNode* root)
    {
        if (root == nullptr) return nullptr;

        root->left = pruneTree(root->left);
        root->right = pruneTree(root->right);

        if (root->left == nullptr && root->right == nullptr && root->val == 0)return nullptr;
        else return root;
    }
};